System and method for fixation of bone fractures

ABSTRACT

The invention facilitates the fixation of bone fractures. In a particular embodiment, the head component includes a tip, cutting threads and mating threads which are inserted into the far cortex of the bone. A wire extends from the head component and exits from the near cortex. A cap device having a sawtooth inner surface is threaded over the wire having an inverse sawtooth outer surface such that the cap is restricted from backwards movement. Tension is then applied to the wire while the cap is tightened against or within the bone surface to thereby apply an appropriate amount of pressure between the surfaces of the fracture. The excess wire beyond the cap can then be removed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S.Provisional Application serial No. 60/330,187, entitled “LAGWIRE SYSTEMAND METHOD” filed Oct. 18, 2001, which is incorporated herein byreference.

FIELD OF INVENTION

The invention generally relates to a system and method for the fixationof fractures in one or more objects, and more particularly, to a lagwiresystem and related components for the fixation of bone fractures.

BACKGROUND OF THE INVENTION

It is well-known in the medical arts that constant pressure on a bonefracture speeds healing. As such, orthopedic physicians typically insertone or more screws in the area of the fracture in order to assertconstant pressure on the bone fracture. However, the insertion ofexisting screws through or around fractures has disadvantages. Forexample, the entire process is very time-consuming because inserting aregular screw usually involves multiple steps such as drilling the pilothole, measuring the relevant distances to determine the appropriatescrew selection, tapping the hole to establish threads and screwing thescrew into the hole. Moreover, when using a lagscrew, the processusually includes even more steps such as drilling through the nearcortex to establish the gliding hole (e.g., 3.5 mm), placing the drillguide in the proper location, drilling through the far cortex (e.g., 2.5mm), measuring the distance to determine the appropriate screwselection, tapping the hole to establish threads and screwing the screwinto the hole, thereby attempting to compress the fracture. Again, eachstep and the entire process is very time-consuming.

In addition to the length and complexity of the process, the prior artsystem also typically includes inadequate components. For example, inpoor bone, prior art screws often loose their grip and strip out of thebone. Currently available lag screws also typically provide only oneside of cortex fixation and are generally not suited for percutaneussurgery. Moreover, when placing the screws in the bone, the physicianmay not accurately set the screw into the distal hole or may miss thedistal hole completely, thereby resulting in the screw stripping thethreads or breaking the bone.

Furthermore, the location and extent of most every fracture is unique,so different screws are often needed for each fracture. Because thephysician typically is unable to accurately determine the type or sizeof screw needed until the physician enters the bone and measures theappropriate screw placement, operating facilities need to store and makeavailable large inventories of screws. Particularly, screws usuallyrange in length from about 10 mm to about 75 mm with available screwsizes limited to every 2 mm there between. Moreover, for each size ofscrew, the screws may be either a cancellous or cortical type, and foreach size and type of screw, the screw may include one of threedifferent pitches. Accordingly, a screw set typically exceeds onehundred screws. Furthermore, if cannulated screws are desired, anotherentire screw set of over one hundred additional screws is often needed.Moreover, each time a screw from a screw set is utilized in a procedure,a replacement screw is typically obtained to complete the set. As such,inventory management of screws is a very large problem for manyoperating facilities. A need exists for a lagwire system whichsimplifies and expedites the process for the fixation of bone fractures,while minimizing the number of components needed in the process.

SUMMARY OF THE INVENTION

In general, the invention facilitates the fixation of bone fractures. Ina particular embodiment, the head component includes a tip, cuttingthreads and mating threads which are inserted into the far cortex of thebone. A wire extends from the head component and exits from the nearcortex. A cap device having a sawtooth inner surface is threaded overthe wire having an inverse sawtooth outer surface such that the cap isrestricted from backwards movement. Tension is then applied to the wirewhile the cap is tightened against or within the bone surface to therebyapply an appropriate amount of pressure between the surfaces of thefracture. The excess wire beyond the cap can then be removed.

The invention also includes a system for facilitating a change indistance between objects, wherein the system includes a head componentconfigured to attach to one of the objects; a wire having a first endand a second end, wherein the first end of the wire is configured tomate with the head component; and, a cap configured to mate with thesecond end of the wire. The invention also includes a method forfacilitating a change in distance between a first and second surface Themethod includes providing a head component mated with a wire having afirst interface component; inserting the head component into the firstsurface by mating a drill over a driver head of the head component tofacilitate drilling the head component into the bone and cutting newthreads into the object using the cutting threads and mating the newthreads with the mating threads; extending the wire through the secondsurface; threading a cap having a second interface component over thefirst interface component of the wire; and removing the excess wirebeyond the cap.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be derived byreferring to the detailed description and claims when considered inconnection with the figures, wherein like reference numbers refer tosimilar elements throughout the figures, and:

FIG. 1 is a lagwire system including a head component and wire inaccordance with an exemplary embodiment of the present invention.

FIG. 2A is a quick cap in accordance with an exemplary embodiment of thepresent invention.

FIG. 2B is an alternative embodiment of a quick cap in accordance withan exemplary embodiment of the present invention.

FIG. 2C is a screw cap in accordance with an exemplary embodiment of thepresent invention.

FIG. 2D is a flat cap in accordance with an exemplary embodiment of thepresent invention.

FIG. 2E is a top view of an alternative embodiment of a cap inaccordance with an exemplary embodiment of the present invention.

FIG. 3 is a tensioner in accordance with an exemplary embodiment of thepresent invention.

FIG. 4A is a fixation of a bone fracture in accordance with an exemplaryembodiment of the present invention.

FIGS. 4B-4D are fixations of fractures of a certain portions of a bonein accordance with an exemplary embodiment of the present invention.

FIG. 4E is a fixation of a bone fracture by inserting the lagwirethrough the entire limb to facilitate attaching an external fixationdevice to the limb in accordance with an exemplary embodiment of thepresent invention.

FIGS. 4F-4G is a fixation of a bone fracture by inserting the lagwirethrough the entire limb to facilitate holding a plate to the bone tohelp fix certain types of fractures in accordance with an exemplaryembodiment of the present invention.

DETAILED DESCRIPTION

The present invention is described herein and includes various exemplaryembodiments in sufficient detail to enable those skilled in the art topractice the invention, and it should be understood that otherembodiments may be realized without departing from the spirit and scopeof the invention. Thus, the following detailed description is presentedfor purposes of illustration only, and not of limitation, and the scopeof the invention is defined solely by the appended claims. Theparticular implementations shown and described herein are illustrativeof the invention and its best mode and are not intended to otherwiselimit the scope of the present invention in any way.

In general, the present invention facilitates the change in distancebetween objects or surfaces, compresses objects together and/or providesa configurable or random amount of pressure between surfaces. The systemmay facilitate changing, maintaining, reducing and/or expanding thedistance between objects. The applied pressure may be suitablyconfigured to be constant, increasing, decreasing, variable, random,and/or the like. In an exemplary embodiment, the invention includes adevice which may be fixedly or removably attached to pathology, such asto a certain portion of a bone. In a particular embodiment, the deviceis fixedly or removably attached to the far cortex of the bone. Inanother embodiment, the invention includes a device or method forretracting the attached device to reduce the distance between thesurfaces of the pathology. In a further embodiment, the inventionincludes a device and/or method for maintaining the pressure between thesurfaces of pathology.

In an exemplary embodiment, and as shown in FIGS. 1 and 2, the lagwiresystem 1 includes a head component 2, a wire 12 and a cap 20. Thelagwire system 1 may be fabricated using any type, amount or combinationof materials suitably configured for the particular application. In anexemplary embodiment for medical applications, the lagwire system 1 isfabricated with stainless steel, titanium and/or titanium alloy whichminimize reactivity with the body. Each component may be fabricated withvarious diameters, thread pitches, lengths and/or the like.

Certain exemplary components of the system will now be discussed. Thehead component 2 is any device which is configured to fixedly orremovably attach to any object, such as pathology. In a particularembodiment, the head component 2 is configured to be fixedly orremovably attached to the far cortex of the bone, as shown in FIGS.4A-4G. As best shown in FIG. 1, the head component 2 may include, forexample, a self drilling tip 4 device which is suitably configured topuncture a hole and/or guide the head component 2, self cutting threads6 which are suitably configured to cut thread grooves into the insidesurface of a hole, fastening threads 8 which are suitably configured tomate with the newly formed thread grooves, and a tool attachment 10suitably configured for mating with a tool head (e.g., hex head wrench,socket wrench, Phillips screwdriver, flathead screwdriver, allan wrenchand/or the like).

In a particular embodiment, the tip is on the front end of headcomponent 2, followed by the cutting threads 6, the fastening threads 8,the tool attachment 10, then wire 12. The elements of head component 2may be fabricated as one component or one or more elements may beconfigured to be removably or fixedly mated together to form headcomponent 2. If mated together, a particular element may be exchangedfor different applications. For example, if head component 2 needs to beinserted into a dense or hard bone, a stronger or sharper tip 4 may bescrewed into thread element 6,8. Moreover, if deeper thread grooves aredesired, cutting threads 6 may be replaced with greater diameterthreads. Furthermore, if a different tool head is incorporated into adrill, tool attachment 10 may be exchanged with the appropriateattachment.

In one embodiment, the outside diameter of the fastening threads aresimilar to the thread diameters of known surgical screw sizes. Exemplaryoutside diameters of cortical head components include 3.5 mm and 4.5 mm,wherein the length of the thread section is similar to the cortexthickness. Exemplary outside diameters of cancellous (i.e., little or nocortex) head components include about 4.0 mm and 6.5 mm, wherein thelength of the thread section may be about 16 mm or 32 mm.

Wire 12 is any device suitably configured, when tension is applied, toreduce the distance between two surfaces. In one embodiment, wire 12 isconfigured to retract the head component 2 device to reduce the distancebetween the surfaces of the pathology. In one embodiment, head component2 and wire 12 are constructed as one component. In another embodiment,head component 2 and wire 12 are constructed as separate components, butthe components are configured such that the head component 2 may bethreaded onto wire 12 after wire 12 is placed into the bone. Wire 12further includes an interface component 14 on at least a portion of itssurface, wherein the interface component 14 is suitably configured tolimit the movement of cap 20 to move distally toward head component 2,but not proximally (backwards). In an exemplary embodiment, interfacecomponent 14 of wire 12 includes a sawtooth like configuration such thatone side of each tooth (e.g. the side closest to head component 2) issubstantially perpendicular to the surface of wire 12, while the otherside of the sawtooth is at a suitable angle, such as 45 degrees, therebyforming a triangular pattern for each sawtooth. In this manner, theinverse sawtooth on the inside surface of the cap slides or bends overthe angled side of the wire sawtooth, but the substantiallyperpendicular side of the wire sawtooth restricts or limits the capsawtooth from backwards movement.

In an exemplary embodiment, wire 12 is comprised of a thin metal suchas, for example, stainless steel, titanium and/or titanium alloy, so itmay be easily cut to almost any desired length, thereby eliminating orreducing the need for fixed lengths screws. As such, the inventionsubstantially reduces or eliminates the need for the inventory oravailability of large screw sets or multiple screws. Moreover, becausethe system may include numerous materials, configurations and designsfor either wire 12 or cap 20, the invention provides increasedversatility because the physician is provided with multiple options andchoices for wire 12 and cap 20 combinations.

Cap 20 is any device suitably configured to maintain or increase thepressure between the surfaces of pathology by limiting wire 12 movement.As shown in FIGS. 2A-2E, exemplary caps 20 may include variousconfigurations, materials, shapes and/or sizes. In one embodiment, andas shown in FIG. 2A, cap 20 includes an inverse interface component 22relative to wire 12 interface component such that cap 20 is restrictedfrom backwards translation after cap 20 is inserted over wire 12. In oneembodiment, the interface component 22 on cap 20 is located at least onthe inside surface of the cap and includes a saw tooth pattern with thesame or similar pitch as the saw tooth on wire 12. This configurationalso allows cap 20 to slide along wire 12 without the need for spinningcap 20 which is important because time is of the essence in a medicalprocedure and spinning the cap down a sufficiently long length of wirewould be very time-consuming. Examples of cap 20 include a screw cap 20,flat cap 20 and a quick cap 20. As shown in FIG. 2C, screw cap 20 isconfigured with teeth 22, cutting threads 24 and/or mating threads 26 onthe outside surface to facilitate rotating cap 20 into the cortex to,for example, fix surgical plates against certain pathology. However,cutting threads 24 may not be needed on any of the caps because cuttingthreads 6 of head component 2 may have already tapped the threads on theinside surface of the bone, so the teeth 22 or mating threads 26 alonecan simply rotatably engage the threads formed from cutting threads 6and provide sufficient friction to secure the cap in the bone. As shownin FIG. 2D, flat cap 20 may include teeth 22, cutting threads 24 and/ormating threads 26 on the outside surface to facilitate rotating cap 20into the cortex, but it also is configured with a flat top surface 28 toallow cap 20 to be inserted into the cortex such that the flat topsurface 28 of cap 20 does not substantially protrude from the cortexsurface. As best shown in FIG. 2A, for example, the quick cap 20 or anyother cap may be configured with only the interface component on theinside surface, thereby allowing for quick and easy assembly.

With reference to FIG. 2E, in one embodiment, cap 20 is configured as aplanar disk 30 with a center hole 32, wherein the center hole 32includes an interface component 34 on its inner circumference surface.In an exemplary embodiment, the pitch of the saw tooth interfacecomponent is about 0.25 mm-0.5 mm. The planar disk 30 may also includeany configuration for facilitating expansion of the disk 36 whilesliding down wire 12. The configurations may include, for example, a cut38 or a hole 36 in the planar disk 30. The planar disk may includemultiple holes or cuts spaced over the planar surface. One or more ofthe additional holes 36 may also be connected to a cut 38 in the planarsurface that extends to the center hole 32. One or more of the holes 36may also be connected to a cut 40 in the planar surface that extends tothe outside edge of the planar surface. In one embodiment, sixadditional holes 36 are evenly spaced around the planar surface witheach hole 36 connected to a cut 38 which extends to the center hole,while one hole 36 also includes a cut 40 that extends to the outsideedge of the planar surface.

The planar disk may also set inside a shallow cup device, wherein thecircumference of the cup is slightly larger than the circumference ofthe planar ring in order to allow expansion of the ring. Moreover, aspring, or any other device suitably configured to apply pressure to cap20, is placed between the planar ring and the cup device. In oneembodiment, a bellville spring is used to apply pressure to the cap 20.The spring is configured to provide tension on wire 12 after resorption.During the healing process, cartilage forms at the break and thecartilage compresses, so bone resorption typically occurs at thelocation of the fracture. When tension on the lagwire is released due tobone resorption during healing, in one embodiment, cap 20 allows forauto tightening of the lagwire because micro-motions or vibrations willoften cause cap 20 interface device 22 to click down another notch onthe inverse interface device of the wire 12.

A tensioner 50 may also be used in conjunction with the presentinvention. With respect to FIG. 3, the tensioner 50 is any devicesuitably configured to insert a cap 20 into an object and/or providetension to a wire 12. In one embodiment, tensioner 50 increases thepressure between the surfaces of pathology by providing tension to awire 12 while the head component 2 of wire 12 is fixed into a bone orfar cortex. In an exemplary embodiment, tensioner 50 includes a handle52 with a hand trigger 54, wherein the handle 52 supports a rotatablebarrel 56 which mates with a cylindrical rod 58. Cylindrical rod 58 maybe cannulated to receive wire 12 and/or have a driver 60 (e.g., hex,phillips, screw, allen and/or the like) at its distal end for matingwith the tool attachment 10 of head component 2. The barrel 56 may berotated manually or automatically in order to rotate the driver 60 intothe object (e.g., bone or cortex). In one embodiment, tensioner 50includes a means for exerting a force on wire 12, such as, for example,internal gears, wherein the gears include an interface component (e.g.,saw tooth) which mate with the inverse sawtooth on wire 12. By pivotingthe hand trigger 54, the internal gears are rotated such that the gearscause wire 12 to translate out the back end 62 of the tensioner 50,thereby exerting tension on wire 12 which is fixed at its distal end.The tensioner 50 may also include a gauge type device or any otherdevice which is suitably configured to measure and/or display thetension exerted on wire 12.

A tensioner 50 may also be used in conjunction with the presentinvention. With respect to FIG. 3, the tensioner 50 is any devicesuitably configured insert a cap 20 into an object and/or providetension to a wire 12. In one embodiment, tensioner 50 increases thepressure between the surf hoes of pathology by providing tension to awire 12 while the bead component 2 of wire 12 is fixed into a bone orfar cortex. In an exemplary embodiment tensioner 50 includes a handle 52with a band trigger 54, wherein the handle 52 supports a rotatablebarrel 56 which mates with a cylindrical rod 58. Cylindrical rod 58maybe cannulated to receive wire 12 and/or have a driver 60 (e.g., hex,phillips, screw, alien and/or the like) at its distal end for matingwith the tool attachment 10 of head component 2. The barrel 56 mayberotated manually or automatically in order to rotate the driver 60 intothe object (e.g., bone or cortex). In one embodiment, tensioner 50includes a means for exerting a force on wire 12, such 35, for example,internal gears ±4, wherein the gears 64 include an interface component66 (e.g., saw tooth) which mate with the inverse sawtooth 20 on wire 12.By pivoting the hand trigger 54, the internal gears are rotated suchthat the gears cause wire 12 to translate out the back end 62 of thetensioner 50, thereby exerting tension on wire 12 which is fixed at itsdistal end. The tensioner 50 may also include a gauge type device or anyother device which is suitably configured to measure and/or display thetension exerted on wire 12.

After attaching the head component 2 to the bone, the surgical drill isremoved and a cap 20 is threaded onto the proximal end 14 of wire 12.Cap 20 is then translated distally along wire 12 until cap 20 contactsthe bone or other desired pathology. In one embodiment, a lagwiretensioner is used to exert tension on the lagwire. In anotherembodiment, a lagwire tensioner 50 may be used to force or seat cap 20into the bone surface or any other desired position. The hex head 60 ofthe tensioner 50 may be used to screw cap 20 into the bone surface. Inanother embodiment, the lagwire tensioner 50 exerts tension on thelagwire 12 up to a desired tension which may be read from a gaugecommunicating with the tensioner.

After positioning the lagwire device 1 and applying the appropriateamount of tension, in one embodiment, the excess wire 12 may be suitablyremoved by, for example, a wire cutter or any other suitable device. Inanother embodiment, a crimp type device may be placed on wire 12 to alsohelp maintain tension. The crimp may include a clamp type device,bending the existing wire 12, screwing a nut onto the end of wire 12and/or the like. The crimp may be placed on wire 12 after cap 20 is setin place, for example, in order to crimp other end pieces together. Thetensioner 50 may also be used to reverse screw cap 20 in order to removea wire 12 out of the bone. Moreover, in a situation where head component2 strips out of the bone (for example, when the bone is of poorquality), the present invention allows the lagwire to be pushed throughthe opposite side of the bone and through the skin such that the headcomponent 2 of wire 12 can be suitably removed (e.g., cut off) and a cap20 can be placed onto that end of the lagwire, thereby resulting inbetter purchase (e.g., quality of fixation) of the bone.

With respect to FIGS. 4A-4G, the lagwire system discussed herein can beused for the fixation of various types of bone fractures. FIG. 4A showsthe use of the present invention for an exemplary fixation of a bonefracture or break. FIGS. 4B-4D show the use of the present invention foran exemplary fixation of fractures of certain portions of bones.Moreover, as shown in exemplary FIGS. 4F and 4G, the lagwire system 1may also be used in a similar manner discussed herein in order to assistin holding a plate to the bone to help fix certain types of fractures.In other types of fractures, the lagwire may be placed through an entirelimb to, for example, attach an external fixation device to the limb asshown in exemplary FIG. 4E.

As described herein, the system and method of the present inventionprovides a device which is self-drilling, self-tapping and can beinserted under power. The invention also facilitates reducing and fixingfractures in one step. As such, the invention substantially expeditesthe process for fixation of bone fractures which is, of course, criticalduring trauma situations in order to stabilize a patient or to minimizethe amount of time the patient is on the operating table or underanesthesia. In contrast to typical prior art screws wherein a glidinghole in the near cortex simply guides the screw, the present inventionprovides the ability for two sides of cortex lag screw fixation.Moreover, because of the strength of the attachment to the bone, theinvention enables sufficient fixation even in poor quality bonematerial. Furthermore, wherein the prior art systems often require theuse of cannulated screws in order to utilize a guidewire for placement,the present invention does not require the use of cannulated screws.Because the lagwire includes a tip 4 which creates a pilot hole, tapsthe bone for threads and fixes the threads into the bone, the system andmethod minimizes the possibility of inaccurate placement into the distalcortex or missing the distal hole.

In prior art systems, the physician typically cuts a relatively largeopening in the skin in order to locate the bone segments, pull the bonesegments into alignment, then place the screw into the bones. In thepresent invention, the system facilitates the percutaneus technique byallowing the physician to cut a minor incision into the skin for thehead component, insert the head component, then pull the bones togetherwith wire 12 and set the cap, all without large incisions or additionalincisions.

The present invention is described herein in connection with thefixation of bone fractures; however, one skilled in the art willappreciate that the lagwire system or method described herein may alsobe used for changing, maintaining, reducing or expanding the distancebetween objects or surfaces, compressing objects together or providingpressure to surfaces. For example, the present invention may be used torepair wood products, tree limb damage, breaks in supports or columns,cracks in sculptures or buildings, breaks in sections of concrete orother building materials, cracks or breaks in car parts and/or the like.

In the foregoing specification, the invention has been described withreference to specific embodiments. Various modifications and changes canbe made, however, without departing from the scope of the presentinvention as set forth in the claims below. The specification andfigures are to be regarded in an illustrative manner, rather than arestrictive one, and all such modifications are intended to be includedwithin the scope of present invention. Accordingly, the scope of theinvention should be determined by the appended claims and their legalequivalents, rather than by the examples given above. For example, thesteps recited in any of the method or process claims may be executed inany order and are not limited to the order presented in the claims.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any element(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as critical, required, or essentialfeatures or elements of any or all the claims. As used herein, the terms“comprises”, “comprising”, “includes”, “including”, or any othervariations thereof, are intended to cover a non-exclusive inclusion,such that a process, method, article, or apparatus that comprises orincludes a list of elements does not include only those elements but mayinclude other elements not expressly listed or inherent to such process,method, article, or apparatus. Further, no element described herein isrequired for the practice of the invention unless expressly described as“essential” or “critical.”

What is claimed is:
 1. A system for facilitating a change in distancebetween objects, said system including: a head component configured toattach to one of said objects; a wire having a tint end and a secondend, wherein said first end of said wire is configured to mate with saidhead component; a cap configured to mate with said second end of saidwire; and a tensioner for applying tension to said wire, wherein saidtensioner includes a cannulated rod configured to receive said wire andgears with a first interface component configured to mate with a secondinterface component of said wire to apply tension to said wire.
 2. Amethod for facilitating a change in distance between a first and secondsurface, said method including: providing a head component mated with awire having a first interface component; inserting said head componentinto said first surface, wherein said head component includes cuttingthreads and mating threads such that said inserting step includescutting new threads into said object using said cutting threads andmating said new threads with said mating threads; extending said wirethrough said second surface; and, threading a cap having a secondinterface component ever said first interface component of said wire.